import torch
import torch.nn as nn

from .backbones.beit import (_make_pretrained_beitb16_384,
                             _make_pretrained_beitl16_384,
                             _make_pretrained_beitl16_512, forward_beit)
from .backbones.levit import _make_pretrained_levit_384, forward_levit
from .backbones.swin import _make_pretrained_swinl12_384
from .backbones.swin2 import (_make_pretrained_swin2b24_384,
                              _make_pretrained_swin2l24_384,
                              _make_pretrained_swin2t16_256)
from .backbones.swin_common import forward_swin
from .backbones.vit import (_make_pretrained_vitb16_384,
                            _make_pretrained_vitb_rn50_384,
                            _make_pretrained_vitl16_384, forward_vit)


def _make_encoder(
    backbone,
    features,
    use_pretrained,
    groups=1,
    expand=False,
    exportable=True,
    hooks=None,
    use_vit_only=False,
    use_readout="ignore",
    in_features=[96, 256, 512, 1024],
):
    if backbone == "beitl16_512":
        pretrained = _make_pretrained_beitl16_512(
            use_pretrained, hooks=hooks, use_readout=use_readout
        )
        scratch = _make_scratch(
            [256, 512, 1024, 1024], features, groups=groups, expand=expand
        )  # BEiT_512-L (backbone)
    elif backbone == "beitl16_384":
        pretrained = _make_pretrained_beitl16_384(
            use_pretrained, hooks=hooks, use_readout=use_readout
        )
        scratch = _make_scratch(
            [256, 512, 1024, 1024], features, groups=groups, expand=expand
        )  # BEiT_384-L (backbone)
    elif backbone == "beitb16_384":
        pretrained = _make_pretrained_beitb16_384(
            use_pretrained, hooks=hooks, use_readout=use_readout
        )
        scratch = _make_scratch(
            [96, 192, 384, 768], features, groups=groups, expand=expand
        )  # BEiT_384-B (backbone)
    elif backbone == "swin2l24_384":
        pretrained = _make_pretrained_swin2l24_384(use_pretrained, hooks=hooks)
        scratch = _make_scratch(
            [192, 384, 768, 1536], features, groups=groups, expand=expand
        )  # Swin2-L/12to24 (backbone)
    elif backbone == "swin2b24_384":
        pretrained = _make_pretrained_swin2b24_384(use_pretrained, hooks=hooks)
        scratch = _make_scratch(
            [128, 256, 512, 1024], features, groups=groups, expand=expand
        )  # Swin2-B/12to24 (backbone)
    elif backbone == "swin2t16_256":
        pretrained = _make_pretrained_swin2t16_256(use_pretrained, hooks=hooks)
        scratch = _make_scratch(
            [96, 192, 384, 768], features, groups=groups, expand=expand
        )  # Swin2-T/16 (backbone)
    elif backbone == "swinl12_384":
        pretrained = _make_pretrained_swinl12_384(use_pretrained, hooks=hooks)
        scratch = _make_scratch(
            [192, 384, 768, 1536], features, groups=groups, expand=expand
        )  # Swin-L/12 (backbone)
    elif backbone == "next_vit_large_6m":
        from .backbones.next_vit import _make_pretrained_next_vit_large_6m

        pretrained = _make_pretrained_next_vit_large_6m(hooks=hooks)
        scratch = _make_scratch(
            in_features, features, groups=groups, expand=expand
        )  # Next-ViT-L on ImageNet-1K-6M (backbone)
    elif backbone == "levit_384":
        pretrained = _make_pretrained_levit_384(use_pretrained, hooks=hooks)
        scratch = _make_scratch(
            [384, 512, 768], features, groups=groups, expand=expand
        )  # LeViT 384 (backbone)
    elif backbone == "vitl16_384":
        pretrained = _make_pretrained_vitl16_384(
            use_pretrained, hooks=hooks, use_readout=use_readout
        )
        scratch = _make_scratch(
            [256, 512, 1024, 1024], features, groups=groups, expand=expand
        )  # ViT-L/16 - 85.0% Top1 (backbone)
    elif backbone == "vitb_rn50_384":
        pretrained = _make_pretrained_vitb_rn50_384(
            use_pretrained,
            hooks=hooks,
            use_vit_only=use_vit_only,
            use_readout=use_readout,
        )
        scratch = _make_scratch(
            [256, 512, 768, 768], features, groups=groups, expand=expand
        )  # ViT-H/16 - 85.0% Top1 (backbone)
    elif backbone == "vitb16_384":
        pretrained = _make_pretrained_vitb16_384(
            use_pretrained, hooks=hooks, use_readout=use_readout
        )
        scratch = _make_scratch(
            [96, 192, 384, 768], features, groups=groups, expand=expand
        )  # ViT-B/16 - 84.6% Top1 (backbone)
    elif backbone == "resnext101_wsl":
        pretrained = _make_pretrained_resnext101_wsl(use_pretrained)
        scratch = _make_scratch(
            [256, 512, 1024, 2048], features, groups=groups, expand=expand
        )  # efficientnet_lite3
    elif backbone == "efficientnet_lite3":
        pretrained = _make_pretrained_efficientnet_lite3(
            use_pretrained, exportable=exportable
        )
        scratch = _make_scratch(
            [32, 48, 136, 384], features, groups=groups, expand=expand
        )  # efficientnet_lite3
    else:
        print(f"Backbone '{backbone}' not implemented")
        assert False

    return pretrained, scratch


def _make_scratch(in_shape, out_shape, groups=1, expand=False):
    scratch = nn.Module()

    out_shape1 = out_shape
    out_shape2 = out_shape
    out_shape3 = out_shape
    if len(in_shape) >= 4:
        out_shape4 = out_shape

    if expand:
        out_shape1 = out_shape
        out_shape2 = out_shape * 2
        out_shape3 = out_shape * 4
        if len(in_shape) >= 4:
            out_shape4 = out_shape * 8

    scratch.layer1_rn = nn.Conv2d(
        in_shape[0],
        out_shape1,
        kernel_size=3,
        stride=1,
        padding=1,
        bias=False,
        groups=groups,
    )
    scratch.layer2_rn = nn.Conv2d(
        in_shape[1],
        out_shape2,
        kernel_size=3,
        stride=1,
        padding=1,
        bias=False,
        groups=groups,
    )
    scratch.layer3_rn = nn.Conv2d(
        in_shape[2],
        out_shape3,
        kernel_size=3,
        stride=1,
        padding=1,
        bias=False,
        groups=groups,
    )
    if len(in_shape) >= 4:
        scratch.layer4_rn = nn.Conv2d(
            in_shape[3],
            out_shape4,
            kernel_size=3,
            stride=1,
            padding=1,
            bias=False,
            groups=groups,
        )

    return scratch


def _make_pretrained_efficientnet_lite3(use_pretrained, exportable=False):
    efficientnet = torch.hub.load(
        "rwightman/gen-efficientnet-pytorch",
        "tf_efficientnet_lite3",
        pretrained=use_pretrained,
        exportable=exportable,
    )
    return _make_efficientnet_backbone(efficientnet)


def _make_efficientnet_backbone(effnet):
    pretrained = nn.Module()

    pretrained.layer1 = nn.Sequential(
        effnet.conv_stem, effnet.bn1, effnet.act1, *effnet.blocks[0:2]
    )
    pretrained.layer2 = nn.Sequential(*effnet.blocks[2:3])
    pretrained.layer3 = nn.Sequential(*effnet.blocks[3:5])
    pretrained.layer4 = nn.Sequential(*effnet.blocks[5:9])

    return pretrained


def _make_resnet_backbone(resnet):
    pretrained = nn.Module()
    pretrained.layer1 = nn.Sequential(
        resnet.conv1, resnet.bn1, resnet.relu, resnet.maxpool, resnet.layer1
    )

    pretrained.layer2 = resnet.layer2
    pretrained.layer3 = resnet.layer3
    pretrained.layer4 = resnet.layer4

    return pretrained


def _make_pretrained_resnext101_wsl(use_pretrained):
    resnet = torch.hub.load("facebookresearch/WSL-Images", "resnext101_32x8d_wsl")
    return _make_resnet_backbone(resnet)


class Interpolate(nn.Module):
    """Interpolation module."""

    def __init__(self, scale_factor, mode, align_corners=False):
        """Init.

        Args:
            scale_factor (float): scaling
            mode (str): interpolation mode
        """
        super(Interpolate, self).__init__()

        self.interp = nn.functional.interpolate
        self.scale_factor = scale_factor
        self.mode = mode
        self.align_corners = align_corners

    def forward(self, x):
        """Forward pass.

        Args:
            x (tensor): input

        Returns:
            tensor: interpolated data
        """

        x = self.interp(
            x,
            scale_factor=self.scale_factor,
            mode=self.mode,
            align_corners=self.align_corners,
        )

        return x


class ResidualConvUnit(nn.Module):
    """Residual convolution module."""

    def __init__(self, features):
        """Init.

        Args:
            features (int): number of features
        """
        super().__init__()

        self.conv1 = nn.Conv2d(
            features, features, kernel_size=3, stride=1, padding=1, bias=True
        )

        self.conv2 = nn.Conv2d(
            features, features, kernel_size=3, stride=1, padding=1, bias=True
        )

        self.relu = nn.ReLU(inplace=True)

    def forward(self, x):
        """Forward pass.

        Args:
            x (tensor): input

        Returns:
            tensor: output
        """
        out = self.relu(x)
        out = self.conv1(out)
        out = self.relu(out)
        out = self.conv2(out)

        return out + x


class FeatureFusionBlock(nn.Module):
    """Feature fusion block."""

    def __init__(self, features):
        """Init.

        Args:
            features (int): number of features
        """
        super(FeatureFusionBlock, self).__init__()

        self.resConfUnit1 = ResidualConvUnit(features)
        self.resConfUnit2 = ResidualConvUnit(features)

    def forward(self, *xs):
        """Forward pass.

        Returns:
            tensor: output
        """
        output = xs[0]

        if len(xs) == 2:
            output += self.resConfUnit1(xs[1])

        output = self.resConfUnit2(output)

        output = nn.functional.interpolate(
            output, scale_factor=2, mode="bilinear", align_corners=True
        )

        return output


class ResidualConvUnit_custom(nn.Module):
    """Residual convolution module."""

    def __init__(self, features, activation, bn):
        """Init.

        Args:
            features (int): number of features
        """
        super().__init__()

        self.bn = bn

        self.groups = 1

        self.conv1 = nn.Conv2d(
            features,
            features,
            kernel_size=3,
            stride=1,
            padding=1,
            bias=True,
            groups=self.groups,
        )

        self.conv2 = nn.Conv2d(
            features,
            features,
            kernel_size=3,
            stride=1,
            padding=1,
            bias=True,
            groups=self.groups,
        )

        if self.bn == True:
            self.bn1 = nn.BatchNorm2d(features)
            self.bn2 = nn.BatchNorm2d(features)

        self.activation = activation

        self.skip_add = nn.quantized.FloatFunctional()

    def forward(self, x):
        """Forward pass.

        Args:
            x (tensor): input

        Returns:
            tensor: output
        """

        out = self.activation(x)
        out = self.conv1(out)
        if self.bn == True:
            out = self.bn1(out)

        out = self.activation(out)
        out = self.conv2(out)
        if self.bn == True:
            out = self.bn2(out)

        if self.groups > 1:
            out = self.conv_merge(out)

        return self.skip_add.add(out, x)

        # return out + x


class FeatureFusionBlock_custom(nn.Module):
    """Feature fusion block."""

    def __init__(
        self,
        features,
        activation,
        deconv=False,
        bn=False,
        expand=False,
        align_corners=True,
        size=None,
    ):
        """Init.

        Args:
            features (int): number of features
        """
        super(FeatureFusionBlock_custom, self).__init__()

        self.deconv = deconv
        self.align_corners = align_corners

        self.groups = 1

        self.expand = expand
        out_features = features
        if self.expand == True:
            out_features = features // 2

        self.out_conv = nn.Conv2d(
            features,
            out_features,
            kernel_size=1,
            stride=1,
            padding=0,
            bias=True,
            groups=1,
        )

        self.resConfUnit1 = ResidualConvUnit_custom(features, activation, bn)
        self.resConfUnit2 = ResidualConvUnit_custom(features, activation, bn)

        self.skip_add = nn.quantized.FloatFunctional()

        self.size = size

    def forward(self, *xs, size=None):
        """Forward pass.

        Returns:
            tensor: output
        """
        output = xs[0]

        if len(xs) == 2:
            res = self.resConfUnit1(xs[1])
            output = self.skip_add.add(output, res)
            # output += res

        output = self.resConfUnit2(output)

        if (size is None) and (self.size is None):
            modifier = {"scale_factor": 2}
        elif size is None:
            modifier = {"size": self.size}
        else:
            modifier = {"size": size}

        output = nn.functional.interpolate(
            output, **modifier, mode="bilinear", align_corners=self.align_corners
        )

        output = self.out_conv(output)

        return output
